docs: def _find_docstring_line(self, start, end):
          """Find the row where a docstring starts in a function or class.
  
          This will search for the first match of a triple quote token in
          row sequence from the start of the class or function.
  
          Args:
              start: the row where the class / function starts.
              end: the row where the class / function ends.
  
          Returns:
              int: the row number where the docstring is found.
          """
          for i in range(start, end + 1):
              if i in self._tokenized_triple_quotes:
                  return i
          return None